I. Evolution of Vegetative Structures

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B. Ferns

1. Examine the pictures of live ferns. How tall are these sporophytes? What structures are specialized for photosynthesis?

Note: Click on image or the word "Magnify" to enlarge

2. Study the cross section of a fern rhizome (an underground stem) of the Cinnamon fern, Osmunda cinnamomea. In the fern, the leaves extend in clusters from an upright position of the stem. Thus, you will find a central vascular region surrounded by a ring of vascular bundles; each smaller bundle extends to a different leaf, or frond. Magnify the image to identify the different structures.

Find:
a. the central vascular region
b. the vascular bundles

Click here to enlarge the image yet again.

Within a vascular bundle find:
a. xylem tracheid cells

As is the case with most ferns, the xylem in this fern is composed of tracheids only. (Remember, lignified cell walls are stained red -- along with tannins and other materials with a net negative charge.)






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